GWEN IFILL: And we move on to Iran and the protests that won’t go away.

Margaret Warner reports.

MARGARET WARNER: The streets of Qom, Iran’s holy city and the center of its religious life, filled with tens of thousands of mourners today. They came both to honor a founding father of modern Iran, Grand Ayatollah Hossein-Ali Montazeri, and to protest the government he had come to oppose.

Montazeri, who died Sunday at age 87, was a patriarch of the Islamic Revolution that swept Iran 30 years ago. At one point, he was designated the successor to the revolution’s founder, Ayatollah Ruhollah Khomeini, but Montazeri was pushed aside when he split with government hard-liners in the late 1980s.

He called for expanding civil liberties and women’s rights and emerged as the senior dissident cleric in Iran. Recently, he even apologized for the 1979 storming of the U.S. Embassy in Tehran and the 444-day hostage crisis that followed.

Montazeri’s legacy of defiance helped inspire and embolden the opposition movement that gained momentum after last June’s disputed presidential election. After President Mahmoud Ahmadinejad was proclaimed the winner amid widespread allegations of fraud, Montazeri penned stinging broadside denouncing the Ahmadinejad government for its handling of the post-election protests.

Those rebukes found a wide audience in Iran and amid the opposition supporters around the world, like Mohsen Sazegara in Northern Virginia.

MOHSEN SAZEGARA, co-founder, Revolutionary Guard: I write down whatever I want to say here in the home video here on a piece of paper.

MARGARET WARNER: Every evening, Sazegara descends to his basement and speaks to tech-savvy reform-minded citizens back in his native Iran. His 10-minute videos counseling tactics of resistance are posted on YouTube, Facebook and Google Mail.

His audience? The thousands of young people and others who, six months after the election, are still taking to the streets of Tehran and elsewhere in protest, as they did today.

Like Montazeri, Sazegara is a somewhat unlikely mentor for them. An aide to Ayatollah Khomeini in the earliest days of the revolution, he went on to help found the Revolutionary Guard, which is now the regime’s main instrument for maintaining control.

Sazegara says his aim is nothing less than bringing down what he calls the coup regime of Ahmadinejad and the supreme leader, Ayatollah Ali Khamenei.

MOHSEN SAZEGARA: The aim of the movement is overthrowing the coup government. And because that the leader is with the coup government leader as well, and he should be tried.

MARGARET WARNER: You were one of the early adherents of this revolution. You helped found the Revolutionary Guard. Why did you turn against it?

MOHSEN SAZEGARA: Because this Revolutionary Guard is not that Revolutionary Guard that I was one of its founders. We wanted to have a people army to defend the country, not an organization which is involved in politics to suppress the people.

One of the pillars of Islamic Revolution was freedom. Independence, freedom, Islamic republic, they were what people shouted on the streets in 1979. But now we have no freedom.

MARGARET WARNER: Anti-government protests hit their peak in the days and weeks immediately after the election. The Revolutionary Guard and its militia, the Basij, responded by beating protesters and throwing many in jail. After show trials for some and death sentences for others, the crowds did diminish, notes Iranian-born Stanford scholar Abbas Milani.

ABBAS MILANI, director of Iranian studies, Stanford University: I think they have succeeded in intimidating some of the people who were sitting on the fence. And they came out in the days after the election in millions. And now that the price of participation has gone up a bit, they are back on the fence.

But I don’t think this is comforting news to the regime, because they have now realized that they are sitting on a potential volcano.

MARGARET WARNER: Resistance is continuing, with protests organized through text messages and Twitter. The regime is fighting back on the P.R. front. It’s been organizing its own pro-government rallies.

It’s also vilifying the opposition with accusations like this new one running on state TV, alleging opposition demonstrators desecrated a photo of the revered Ayatollah Khomeini. And, most recently, government-linked newspapers and political figures have been calling for the arrest of senior opposition leaders, including the reform politician who claims to have actually won the election, Mir Hossein Mousavi.

ABBAS MILANI: If at any time the regime thought that they could get away with arresting him, I think they would. I think the only thing that is barring it is that they know that they are sitting on this seething volcano. They don’t want to take a risk. They don’t want to do something that they don’t know the results of. And this is one of the biggest risks, I think, that they would have to take.

MARGARET WARNER: All this takes place against the backdrop of mounting tensions with the United States and the West over Iran’s nuclear program, its repeated missile tests, and the fate of three American hikers who strayed across the border and are now facing trial for espionage.

Yet, stability at home remains the regime’s top priority. In a recent meeting with clerics, Supreme Leader Ayatollah Khamenei said, the government would remain stable and the opposition will be destroyed before your eyes.

But Mohsen Sazegara insists there are significant splits in the clergy and even in the Revolutionary Guard.

Do you think this opposition movement, which you’re helping to inspire as well, can really bring down this regime?

MOHSEN SAZEGARA: Yes, I think so. While we are going ahead, we can see that many gaps in this society, for instance, gender gap, generation gap, minorities gap, social class gap, and the gap between knowledge and ignorance of the regime, knowledge of a nation and ignorance of a regime, they are big motivations for a nation to uprise for her rights.

MARGARET WARNER: Opposition leaders say they plan to show their muscle again next Sunday on the major Shiite religious holiday of Ashura. It will coincide with the seventh day of mourning for Montazeri, adding to the expected outpouring in the streets. What isn’t at all clear is how long the regime will tolerate this kind of public dissent.

With two such determined foes, it would appear that this drama in Iran has many chapters to play out.

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